Australian Oil Circuit Breaker Failure

Mervyn Davies and Steve Vlahovic from PowerWater with the broken unit that caused the power outage. Picture: NICK WELSH

33KV Oil Circut Breaker CT Upgrade

33 KV Oil Circuit Breaker destruction, fire

October 11th, 2008 - Australia's NT Power and Water Authority reported that heat caused by friction inside a circuit breaker led to the explosion at Casuarina substation that has caused major blackouts in Darwin's northern suburbs.

Mervyn Davies, who headed the inquiry into the substation failures, revealed yesterday how the initial explosion occurred that has led to the series of power outages. Mr Davies said general wear and tear had led to increased friction inside one of the oil-filled circuit breakers at the substation. This had led to the intense heat that caused the explosion. The investigation brought in senior expertise in utility quality HV electrical distribution maintenance from New South Wales.

Mr Davies said the model of the circuit breaker installed at the substation after Cyclone Tracy had a common design fault. But he said there was no imminent danger of other circuit breakers exploding.

"I can never say it won't happen again but in the last two days we have done some very crucial assessment of the assets and we now feel more confident about their imminent likelihood of failure," he said.

Power and Water has started rolling out generators around the suburbs to ensure power supply is guaranteed in the event of another failure at the substation.

Power and Water managing director Andrew Macrides said power outages had been scheduled in Brinkin and Leanyer next week for essential maintenance work.